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US 6,323,738 B1Granted
Voltage-controlled ring oscillator with level converting and amplitude control circuits
AssigneeKabushiki Kaisha Toshiba
InventorsAkihiko Yoshizawa, Shuichi Takada
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Abstract
A voltage-controlled oscillator comprises a level converting circuit, an amplitude controller, a voltage-controlled oscillation section having differential delay cells connected in a ring form, and an output level converting circuit. The level converting circuit has limiters which respectively limit a maximum value and a minimum value of a control current. Those limiters permit only a region where the voltage-controlled oscillation section properly performs its oscillating operation to be used.
Claims27
A voltage-controlled oscillator comprising a level converting circuit which includes:
- a V/I converting section for converting an input control voltage to a control current for controlling a voltage-controlled oscillation section;
- a first limiter for limiting a maximum value of said control current with respect to said converted current;
- a second limiter for limiting a minimum value of said control current;
- and
- a constant current source for generating a reference current for said first and second limiters.
2 more elements
A voltage-controlled oscillator having a voltage-controlled oscillation section and an amplitude controller for controlling an amplitude of a signal output from said voltage-controlled oscillation section,
- said voltage-controlled oscillation section having a plurality of differential delay cells connected in a ring form, each of said differential delay cells including first amplitude control means, first V/I converting means having an input terminal to which a differential signal is input, and first current control means to which an output current of said first V/I converting means is commonly supplied,
- said amplitude controller including,
- an amplitude-control target circuit having second amplitude control means, second V/I converting means whose input terminal is applied with a supply voltage and which is controlled by an output of said second amplitude control means, and second current control means to which an output current of said second V/I converting means is supplied,
- a reference voltage generator for generating and outputting a reference voltage for amplitude control, and
- an operational amplifier for receiving said reference voltage output from said reference voltage generator and an output voltage of said amplitude-control target circuit and outputting a control voltage for controlling said first amplitude control means in said differential delay cells and said second amplitude control means in said amplitude-control target circuit in such a way that a potential difference between said reference voltage and said output voltage becomes zero,
- wherein a difference between a lower limit of an oscillation amplitude of said differential delay cells which are performing an AC operation and said output voltage of said amplitude-control target circuit which is performing a DC operation is corrected by said control voltage output from said operational amplifier.
3 more elements
A voltage-controlled oscillator comprising a voltage-controlled oscillation section and an amplitude controller for controlling an amplitude of a signal output from said voltage-controlled oscillation section,
- said voltage-controlled oscillation section having a plurality of differential delay cells connected in a ring form, each of said differential delay cells including a first amplitude control section, first and second V/I converting sections having input terminals to which differential signals are input, and a first current control section to which output currents of said first and second V/I converting sections are commonly supplied,
- said amplitude controller including,
- an amplitude-control target circuit having a second amplitude control section, a third V/I converting section whose input terminal is applied with a supply voltage and which is controlled by an output of said second amplitude control section, a fourth V/I converting section whose input terminal is supplied with an output voltage of said third V/I converting section and which is controlled by said output of said second amplitude control section, and a second current control section to which output currents of said third and fourth V/I converting sections are commonly supplied and whose current value is equal to that of said first current control section,
- a reference voltage generator for generating and outputting a reference voltage for amplitude control, and
- an operational amplifier for receiving said reference voltage output from said reference voltage generator and an output voltage of said amplitude-control target circuit and outputting an amplitude control voltage for controlling said first amplitude control sections in said differential delay cells and said second amplitude control section in said amplitude-control target circuit in such a way that a potential difference between said reference voltage and said output voltage becomes zero,
- wherein a transconductance of said second amplitude control section of said amplitude-control target circuit is greater than a transconductance of said first amplitude control sections of said differential delay cells constituting said voltage-controlled oscillation section with respect to the same control voltage output from said operational amplifier.
3 more elements
A voltage-controlled oscillator comprising a voltage-controlled oscillation section having a plurality of differential delay cells connected in a ring form, and an amplitude controller for controlling an amplitude of a signal output from said voltage-controlled oscillation section,
- said amplitude controller including,
- an amplitude-control target circuit,
- a reference voltage generator for generating and outputting a reference voltage for amplitude control, and
- an operational amplifier for receiving said reference voltage output from said reference voltage generator and an output voltage of said amplitude-control target circuit and outputting a control voltage for controlling amplitude control sections in said differential delay cells and an amplitude control section in said amplitude-control target circuit in such a way that a potential difference between said reference voltage and said output voltage becomes zero,
- each of said differential delay cells having a first amplitude control section and a first current control section and a pair of first and second V/I converting sections connected between said first amplitude control section and said first current control section, differential signals being input to input terminals of said first and second V/I converting sections,
- said amplitude-control target circuit having a second amplitude control section and a second current control section and a single third V/I converting section connected between said second amplitude control section and said second current control section, a supply voltage being input to an input terminal of said third V/I converting section.
3 more elements
A voltage-controlled oscillator comprising a voltage-controlled oscillation section and an amplitude controller for controlling an amplitude of a signal output from said voltage-controlled oscillation section,
- said voltage-controlled oscillation section having a plurality of differential delay cells connected in a ring form, each of said differential delay cells including a first amplitude control section, first and second V/I converting sections having input terminals to which differential signals are input, and a first current control section to which output currents of said first and second V/I converting sections are commonly supplied,
- said amplitude controller including,
- an amplitude-control target circuit having a second amplitude control section, a third V/I converting section whose input terminal is applied with a supply voltage and which is controlled by an output of said second amplitude control section, and a second current control section to which an output current of said third V/I converting section is supplied and whose current value is smaller than a current value of said first current control section and greater than ½ thereof,
- a reference voltage generator for generating and outputting a reference voltage for amplitude control, and
- an operational amplifier for receiving said reference voltage output from said reference voltage generator and an output voltage of said amplitude-control target circuit and outputting an amplitude control voltage for controlling said first amplitude control sections in said differential delay cells and said second amplitude control section in said amplitude-control target circuit in such a way that a potential difference between said reference voltage and said output voltage becomes zero,
- wherein a transconductance of said first amplitude control sections of said differential delay cells constituting said voltage-controlled oscillation section is substantially equal to a transconductance of said second amplitude control section of said amplitude-control target circuit with respect to the same control voltage output from said operational amplifier.
3 more elements
A voltage-controlled oscillator comprising a voltage-controlled oscillation section and an amplitude controller for controlling an amplitude of a signal output from said voltage-controlled oscillation section,
- said voltage-controlled oscillation section having a plurality of differential delay cells connected in a ring form, each of said differential delay cells including a first amplitude control section, first and second V/I converting sections having input terminals to which differential signals are input, and a first current control section to which output currents of said first and second V/I converting sections are commonly supplied,
- said amplitude controller including,
- an amplitude-control target circuit having a second amplitude control section, a third V/I converting section whose input terminal is applied with a supply voltage and which is controlled by an output of said second amplitude control section, and a second current control section to which an output current of said third V/I converting section is supplied and whose current value is substantially ½ of a current value of said first current control section,
- a reference voltage generator for generating and outputting a reference voltage for amplitude control, and
- an operational amplifier for receiving said reference voltage output from said reference voltage generator and an output voltage of said amplitude-control target circuit and outputting an amplitude control voltage for controlling said first amplitude control sections in said differential delay cells and said second amplitude control section in said amplitude-control target circuit in such a way that a potential difference between said reference voltage and said output voltage becomes zero,
- wherein a transconductance of said second amplitude control section of said amplitude-control target circuit is smaller than a transconductance of said first amplitude control sections of said differential delay cells constituting said voltage-controlled oscillation section with respect to the same control voltage output from said operational amplifier.
3 more elements
A voltage-controlled oscillator comprising an output level converting circuit which includes:
- a small-amplitude output and low-gain input differential stage for receiving and amplifying a small-amplitude output signal of a voltage-controlled oscillation section comprised of differential delay cells;
- an output level adjusting circuit for adjusting a DC level of an output of said small-amplitude output and low-gain input differential stage;
- a common-mode feedback amplifying stage for receiving an output of said small-amplitude output and low-gain input differential stage whose output level has been adjusted and amplifying said received output to an output of a CMOS level;
- and
- a CMOS buffer amplifying stage for receiving an output of said common feedback amplifying stage and outputting a waveform-shaped output signal.
2 more elements
Dependencies are inferred from the claim text.